Existing toilet cisterns make use of a float valve to control the flow of water into a cistern, from which the water is flushed into toilet bowl under action of gravity on the water in the cistern. A lot of water is required with this system to clear the toilet trap and sewer, between 9 and 13 litres of water are typical. If water can be saved per flush, millions of litres can be saved on a daily basis in many countries of the world.
The inflow of water into a cistern is controlled by a float valve, the result is that it takes quite a while for the cistern to be filled and to be ready for the next flush. This results in public toilets in the bowl often being dirty as the toilet is not ready for the next flush quickly enough.
Because the float valve progressively restricts the inflow of water as the cistern approaches full, a considerable noise is associated with the filling. This noise is particularly objected to in domestic installation.
These three problems with toilet cisterns are in need of a solution.
Time delay valves have been used to flush a toilet bowl, but are not a completely satisfactory solution. The valves limit the flow rate of the flush so that again a lot of water is required to clear the trap and sewer. They have been used more successfully in urinals. The valves also tend to be unreliable.
A design has been proposed that uses an electrically motorised pump to produce the flush that it claims is a powerful and quiet action, with a dual flush option. Whether these claims are met or not is uncertain, but the device has undoubted technical complexity and resulting cost and the undesirable combination of electricity and water, in a domestic or personal use appliance.
The term “toilet” used herein refers to the fixture used to defecate or urinate and having a means of flushing.
There is a need to find a better flushing means.